1. Field of the Invention
This invention relates to an IP telephone apparatus and an IP telephone system including an Internet telephone function in addition to a general telephone function provided through a public switched telephone network.
2. Background Art
The Internet telephone means a telephone conversation mode in which a packet carrying a voice is transferred in a two-way manner via the Internet. A related art to the Internet telephone for enabling a user to use both the Internet telephone and general telephone (ordinary telephone) functions (for example, refer to JP-A-10-155034) and the like are known.
In the related art, the user can use both the Internet telephone and general telephone functions from the telephone main unit, but cannot use the Internet telephone function from an external telephone including only the general telephone function. Particularly, the user who owns an apparatus for enabling the user to use the Internet telephone function and a telephone including only the general telephone function may want to also use the Internet telephone function at low communication costs from the telephone including only the general telephone function.